Wipe material with nanofiber layer

ABSTRACT

A flexible wipe comprising at least one conformable non-woven layer and at least one adhered nanofiber layer can be used to remove a variety of particulate soils from planar, curved or complex surfaces. The nanofiber layer is configured onto the flexible non-woven in a fashion such that particulate of a broad particle size range is trapped by the nanofiber layer and efficiently removed from the contaminated surface. The nanofiber layer comprises a web of spun fibers that can incorporate and trap soil particles for efficient soil removal.

FIELD OF THE INVENTION

[0001] The invention is embodied in a surface shape conformable andflexible wipe having at least two layers of material. The wipecomprising a nanofiber layer and a flexible fabric substrate, can removesoils in the form of inorganic or organic particulate, oily or greasysoils, or dispersions of particulate in liquid. The wipe has a layerspecifically designed to incorporate finely divided small particle sizesoil for efficient removal from a variety of contaminated surfaces. Thelayer can also absorb oily or greasy soils onto the fiber substrate.Further, when used with appropriate liquid (aqueous or organic)cleaning, dusting or other such compositions, the fine fiber layer canobtain an improved surface appearance due to the reduced size of anystructure formed from cleaning compositions.

BACKGROUND OF THE INVENTION

[0002] Both woven and non-woven fabrics have been used for many yearsfor cleaning and polishing purposes. Such fabrics are typicallymanufactured by forming fiber into a woven or non-woven structure. Thesefabrics must conform to the contaminated surfaces for the purposes ofeither dry wiping (dusting) or wet wiping (with water or liquid cleanersor polishing composition) particulate, organic or inorganic soils, fromladen surfaces. Such particulates are commonly considered soils andtheir removal is highly desirable in many environments for maintainingcleanliness, human health, improved production efficiency or through theremoval of biological, chemical or radioactive contamination. Thesematerials can also be used to renew or polish surfaces using finishingcompositions to form a shining surface. Generally, the woven andnon-woven fabrics have an absorbent assembly of fibers. Conventionalcloths can often remove particulate at some level of efficiency and,when used wet, be able to absorb quantities of liquid material either asa result of liquid contamination or through the application of liquidcleaners to a soiled surface. Examples of conventional fabrics includeNankee et al., U.S. Pat. No. 3,686,024; Lindsey et al., U.S. Pat. No.4,260,443; Packard et al., U.S. Pat. No. 4,851,069 and Makoui EuropeanPatent Application No. 35 96 15. In large part, these wipes arecellulosic composites that interact with water to obtain efficientcleaning capacity.

[0003] The prior art has also recognized that fine fiber materials canbe included in such structures. Such structures are shown in Anderson etal., U.S. Pat. No. 4,100,324; Meitner, U.S. Pat. No. 4,307,143; Andersonet al., U.S. Pat. No. 5,651,862 and Torobin, U.S. Pat. No. 6,269,513.These nanofiber containing structures rely on a technology in which thenanofibers, in the form of reduced lengths of fiber, are incorporatedand distributed throughout the non-woven or woven matrix and combinedwith other fiber in the fiber mass. No discrete fine fiber layer isfound in or on the wipe. The fine fiber inside the layers allegedlyimproves cleaning properties of the pad or composite material.

[0004] Our experience with conventional woven and non-woven wipes, eventhose containing nanofiber dispersed in the bulk material, is that thesewipes have adequate, conventional cleaning properties. The wipes oftenfail to substantially remove small particulate in a cleaning mode. Thelarge fiber part of these materials results often in a level of finishformation not acceptable to users. Accordingly, a substantial needexists for new conformable wipe configurations that are adapted totrapping and removing small particulate contaminant from surfaces. Suchwipes can substantially improve cleaning efficiency by removing smallparticulate, soils, bacteria, chemical and biological contaminants andpotentially radioactive materials as well. Such wipes, with reducedfiber size can form an improved surface finish by reducing surfacedefects.

BRIEF DESCRIPTIONS OF THE INVENTION

[0005] The wipe structure constituting an aspect of the inventioncomprises at least a flexible conformable fabric substrate layer havingdiscrete sides and a discrete fine fiber layer formed on at least oneside of the substrate.

[0006] The fabric substrate used in making the wipe of the invention cancomprise either a woven or non-woven fabric having a thickness of about0.01 to 0.2 cm or about 0.02 to 0.1 cm, made from natural or syntheticmaterials. Natural materials include cotton or flax fibers. Syntheticpolymer materials are known in the art. Many useful fabric substratescomprise a mixed cellulosic/synthetic, non-woven fabric made bycombining cellulosic fiber with synthetic fibers such as polyolefins,polyesters, etc.

[0007] The fine fiber layer of the invention comprises a layer having alayer thickness of about 0.05 to 30 millimeters, a fiber diameter ofabout 0.05 to 0.5 microns, a basis weight of about 0.0012 to 3.5 gramsper meter² and a pore size that ranges from about 0.5 to 20 microns. Thepresence of the very small diameter fine fiber (compared to conventionalfibers) permits the fine fiber to incorporate inorganic particulate andabsorb organic soil in cleaning operations. In polishing operations, thesmall dimensions of the fine fiber results in improved surfacecharacteristics derived from polishing or first coating applications.The fine fiber layer on the flexible wipe of the invention provides aweb of fibers having a smaller dimension than conventional cleaningwipes. Such small fibers, when used with a material that forms a surfacefinish or coating on a cleaning surface, can obtain a smoother, shinier,more aesthetically pleasing appearance. Any finish formed using the finefiber layer will have an improved surface finish resulting from theimproved surface characteristics left by the smaller fiber of the finefiber layer. The fine fiber forms fewer and smaller defects than largerfiber wipes. Accordingly, the fine fiber wipes of the invention can beused in a process that forms an improved finish on a cleanable surfaceby contacting the surface with a composition that can form a coating onthe surface, wiping the surface with a fine fiber layer (eithersaturated with the composition or with a composition pre-applied to thesurface), distributing the coating and permitting the coating to formits final improved characteristic.

[0008] For the purpose of this disclosure, the term “inorganicparticulate” typically refers to finely divided particulate soilsderived from the environment including dust and dirt particulates havinga particle size of about 10⁻³ to 10⁵ micron, often 10⁻² to 10 micron.The term “organic soils” typically include soils derived from humanoccupation, foods, cosmetics, cleaners, or common organic materials fromthe human environment. Often, such organic and inorganic soils can becombined with small particulate organic matter such as skin cells,insects and insect parts, etc.

[0009] One important characteristics of the wipe is the flexibility ofthe wipe and the flexibility of the fine fiber layer. While the polymersof the invention display flexural properties similar to unfilledpolymer, the small fiber diameter gives the fiber on the wipe a uniqueflexibility and improved cleaning/polishing character. Cleaning pressurecan bring the fine fiber into intimate contact with the soil, thesurface regardless of its complexity. In contact with the soils, theunique nature of the fine fiber causes the fiber to combine with thesoils and trap or accumulate soils as the fiber layer is mechanicallystretched, wrapped and changed. In a polishing mode, the fiber smallsize can form an improved surface coating due to the coating having areduced defect character due the size of the fiber. Larger conventionalfiber leaves larger defects in the finished coating. In the wipesubstrate, many synthetic and natural fiber materials are available thathave substantial stiffness. Such materials cannot be made sufficientlyflexible to be able to easily comply with complex surfaces faced byindividuals who wish to clean or polish such surfaces. The wipes shouldbe manufactured from a material that is flexible and easily conformableto the surface. The term “conformable” means that the wipe and the finefiber layer can be placed into contact with a surface for cleaningproposes even with surfaces that have complex angled or curved surfaces.Minimal pressure can bring the fine fiber layer into intimate contactwith substantially all surfaces of a complex article.

BRIEF DESCRIPTION OF THE FIGURES

[0010] FIGS. 1-17 are scanning electron-photo micrographs (SEMS) ofwipes with a nanofiber layer that have been used to remove bothinorganic particulate and organic soils form a automotive glass surfaceor a polymeric dash surface. The figures show that the fibers can trapboth organics and inorganic soils. Small particulate is enmeshed by thefiber while the organic soils coat the fibers on contact between thefiber and soil. The interaction of the surface and soil with the finefiber layer changes the conformation of the fiber layer as the fiberstrap particulate and accumulate organic soil.

DETAILED DISCUSSION OF THE INVENTION

[0011] The web of the invention comprises at least a two-layerstructure. The first layer comprises a flexible, conformable, woven ornon-woven fabric layer having a second layer comprising a nanofibermaterial. The conformable wipe can be applied to any flat, convex,concave or complex surface for the purpose of removing inorganic ororganic soils or for the purpose of restoring a shiny, pleasingappearance to the surface.

[0012] For the purpose of this patent application, the term “fine fiber”refers to a fiber having an indeterminate length but a width of lessthan about 5 microns often, less than about 1 micron. In the wipe, thefine fiber is formed into a randomly oriented mesh of fiber in a layerthat substantially covers a surface of the fabric substrate. Preferredfine fiber add-on parameters are as follows: Dimensions Range Layerthickness (μm) 0.1 to 5 Solidity % 5 to 40 Density (gm-cm⁻³) 0.9 to 1.6(1.2 to 1.4) Basis wt. (mg-cm⁻²) 1.2 × 10⁻⁴ to 3.5

[0013] In one embodiment, a reduced amount but useful add-on amount offine fiber would be a 0.1 to 1.75 micron thick layer of 5% to 40%solidity fiber layer (95% to 60% void fraction). In this case the basisweight is 4×10⁻⁴ to 0.11 mg-cm⁻².

[0014] In another embodiment, an add-on amount of fine fiber would a0.75 to 1.25 micron thick layer of 15% to 25% solidity fiber layer (85%to 75% void fraction) In this case the basis weight is 1.0×10⁻² to 0.05mg-cm⁻²

[0015] In a final embodiment, the upper end of the add-on amount of finefiber would be a 0.1-3 micron thick layer of 10% to 40% solidity fiberlayer (90% to 60% void fraction). In this case the basis weight is4×10⁻⁴ to 0.2 mg-cm⁻².

[0016] For the purpose of this disclosure, the term “separate from fiberlayer” is defined to mean that in the wipe structure, having asubstantially sheet-like substrate, the fine fiber layer substantiallycovers the fabric substrate. The fine fiber layers can in theory bemanufactured in one processing step that covers the entirety of one orboth surfaces of a two sided flexible fabric. In most applications, weenvision that a first fine fiber layer will be formed on one fabricside.

[0017] For the purpose of this disclosure, the term “fine fiber layerpore size or fine fiber web pore size” refers to a space formed betweenthe intermingled fibers in the fine fiber layer.

[0018] For the purpose of this disclosure, the term “fabric or fabricsubstrate” refers to a woven or non-woven sheet like substrate, having athickness of about 0.1 to 5 millimeters.

[0019] The wipe includes at least a fine fiber or nanofiber web layer incombination with a fabric substrate material in a mechanically stablestructure. The fine fiber layer must be sufficiently mechanically andchemically stable to obtain cleaning or polishing through interactionwith soil and surface. These layers together provide excellent organicabsorption, surface conformation, and high particle capture. After usethe polymer fiber or fiber web may be substantially changed in physicalconformation. Mechanical forces of wiping can substantially consolidatethe fine fiber layer and distort the fine fiber substantially form itsinitial form. The wipes of the invention are manufactured by spinningfine fiber and then forming an interlocking web of microfiber on aporous wipe fabric substrate. In the spinning process the fiber can formphysical bonds between fibers to interlock the fiber mat into anintegrated layer on the fabric. Such a material can then be fabricatedinto the desired wipe format such as a dry or wet wipe.

[0020] The invention relates to polymeric compositions with improvedproperties that can be used in a variety of applications including theformation of nanofibers, fiber webs, fibrous mats, etc. The fine fibersthat comprise the micro- or nanofiber containing layer of the inventioncan be fiber and can have a diameter of about 0.001 to 2 micron,preferably 0.05 to 0.5 micron. The thickness of the typical fine fiberlayer ranges from about 1 to 100 times the fiber diameter with a basisweight ranging from about 4.5×10⁻⁴ to 2 mg-cm⁻².

[0021] The fine fiber-containing wipe of the invention can be used toclean virtually any soil or contaminated surfaces. Such surfaces caninclude surfaces in the home including metal, plastic, wood, glass orother common household surface. Surfaces found in industry includingprocess equipment, instrumentation, computer equipment, communicationsequipment, etc. Surfaces common in the hospital environment such asinstrumentation, beds, gurneys, operating theater environments,laboratory environments, etc. Other important surfaces include surfacesthat may be contaminated by chemical or biological agents, radioactiveagents derived from weapon research, manufacture or terrorist threat.Other surfaces can be surfaces of parts of the human body. The wipes canbe used for medical, hygienic or cosmetic purposes. Such applicationsinclude baby wipes, medical wipes; cosmetic wipes facial wipes orflushable materials. Such surfaces can be substantially planar, formedinto simple curves or configured into complex shapes having complexcurvature, sharp edges, corners or grooves. Such surfaces can becontaminated with either organic or inorganic soils or combinationsthereof. As a result, the wipe of the invention must be flexible andconformable to any surface requiring cleaning or polishing. The wipemust be sufficiently flexible such that the nanofiber layer can contactsubstantially the entire surface during cleaning operations. The finefiber layer must come into contact with organic, inorganic orparticulate soils in order to permit the fine fiber to obtain theorganic soils as a coating on the fiber and to enmesh the particulatesoil in the fine fiber structure. As can be seen in the photomicrographsshown in FIGS. 1 through 17 of the invention, the fine fiber materialsof the invention are engineered such that the fiber can enmeshparticulate soil and can absorb organic soil onto the surface of thefiber for cleaning purposes. This property is the result of both thechemical nature of the fine fiber and its size and distribution in thefine fiber layer.

[0022] Polymeric materials have been fabricated in non-woven and wovenfabrics, fibers and microfibers. The polymer materials that can be usedin the fine fiber or the polymeric fiber fabric compositions of theinvention include both addition polymer and condensation polymermaterials such as polyolefin, polyacetal, polyamide, polyester,cellulose ether and ester, polyalkylene sulfide, polyarylene oxide,polysulfone, modified polysulfone polymers and mixtures thereof.Preferred materials that fall within these generic classes includepolyethylene, polypropylene, poly(vinylchloride), polymethylmethacrylate(and other acrylic resins), polystyrene, and copolymers thereof(including ABA type block copolymers), poly(vinylidene fluoride),poly(vinylidene chloride), polyvinylalcohol in various degrees ofhydrolysis (87% to 99.5%) in crosslinked and non-crosslinked forms.Preferred addition polymers tend to be glassy (a Tg greater than roomtemperature). This is the case for polyvinylchloride andpolymethylmethacrylate, polystyrene polymer compositions or alloys orlow in crystallinity for polyvinylidene fluoride and polyvinylalcoholmaterials. One class of polyamide condensation polymers include nylonmaterials. The term “nylon” is a generic name for all long chainsynthetic polyamides. Typically, nylon nomenclature includes a series ofnumbers such as in nylon-6,6 which indicates that the starting materialsare a C₆ diamine and a C₆ diacid (the first digit indicating a C₆diamine and the second digit indicating a C₆ dicarboxylic acidcompound). Another nylon can be made by the polycondensation of epsiloncaprolactam in the presence of a small amount of water. This reactionforms a nylon-6 (made from a cyclic lactam—also known asepisilon-aminocaproic acid) that is a linear polyamide. Further, nyloncopolymers are also contemplated. Copolymers can be made by combiningvarious diamine compounds, various diacid compounds and various cycliclactam structures in a reaction mixture and then forming the nylon withrandomly positioned monomeric materials in a polyamide structure. Forexample, a nylon 6,6-6,10 material is a nylon manufactured fromhexamethylene diamine and a C₆ and a C₁₀ blend of diacids. A nylon6-6,6-6,10 is a nylon manufactured by copolymerization ofepsilonaminocaproic acid, hexamethylene diamine and a blend of a C₆ anda C ₁₀ diacid material.

[0023] Block copolymers are also useful in the process of thisinvention. With such copolymers the choice of solvent swelling agent isimportant. The selected solvent is such that both blocks were soluble inthe solvent. One example is an ABA (styrene-EP-styrene) or AB(styrene-EP) polymer in methylene chloride solvent. If one component isnot soluble in the solvent, it will form a gel. Examples of such blockcopolymers are Kraton® type of styrene-b-butadiene andstyrene-b-hydrogenated butadiene (ethylene propylene), Pebax® type ofe-caprolactam-b-ethylene oxide, Sympatex® polyester-b-ethylene oxide andpolyurethanes of ethylene oxide and isocyanates.

[0024] Addition polymers like polyvinylidene fluoride, syndiotacticpolystyrene, copolymer of vinylidene fluoride and hexafluoropropylene,polyvinyl alcohol, polyvinyl acetate, amorphous addition polymers, suchas poly(acrylonitrile) and its copolymers with acrylic acid andmethacrylates, polystyrene, poly(vinyl chloride) and its variouscopolymers, poly(methyl methacrylate) and its various copolymers, can besolution spun with relative ease because they are soluble at lowpressures and temperatures. However, highly crystalline polymer likepolyethylene and polypropylene require high temperature, high pressuresolvent if they are to be solution spun. Therefore, solution spinning ofthe polyethylene and polypropylene is very difficult. Electrostaticsolution spinning is one method of making nanofibers and microfiber.

[0025] We have also found a substantial advantage to forming polymericcompositions comprising two or more polymeric materials in polymeradmixture, alloy format or in a crosslinked chemically bonded structure.We believe such polymer compositions improve physical properties bychanging polymer attributes such as improving polymer chain flexibilityor chain mobility, increasing overall molecular weight and providingreinforcement through the formation of networks of polymeric materials.

[0026] In one embodiment of this concept, two related polymer materialscan be blended for beneficial properties. For example, a high molecularweight polyvinylchloride can be blended with a low molecular weightpolyvinylchloride. Similarly, a high molecular weight nylon material canbe blended with a low molecular weight nylon material. Further,differing species of a general polymeric genus can be blended. Forexample, a high molecular weight styrene material can be blended with alow molecular weight, high impact polystyrene. A Nylon-6 material can beblended with a nylon copolymer such as a Nylon-6; 6,6; 6,10 copolymer.Further, a polyvinylalcohol having a low degree of hydrolysis such as a87% hydrolyzed polyvinylalcohol can be blended with a fully orsuperhydrolyzed polyvinylalcohol having a degree of hydrolysis between98 and 99.9% and higher. All of these materials in admixture can becrosslinked using appropriate crosslinking mechanisms. Nylons can becrosslinked using crosslinking agents that are reactive with thenitrogen atom in the amide linkage. Polyvinylalcohol materials can becrosslinked using hydroxyl reactive materials such as monoaldehydes,such as formaldehyde, ureas, melamine-formaldehyde resin and itsanalogues, boric acids and other inorganic compounds. dialdehydes,diacids, urethanes, epoxies and other known crosslinking agents.Crosslinking technology is a well known and understood phenomenon inwhich a crosslinking reagent reacts and forms covalent bonds betweenpolymer chains to substantially improve molecular weight, chemicalresistance, overall strength and resistance to mechanical degradation.

[0027] The fine fiber can be made of a polymer material or a polymerplus additive. One preferred mode of the invention is a polymer blendcomprising a first polymer and a second, but different polymer(differing in polymer type, molecular weight or physical property) thatis conditioned or treated at elevated temperature. The polymer blend canbe reacted and formed into a single chemical specie or can be physicallycombined into a blended composition by an annealing process. Annealingimplies a physical change, like crystallinity, stress relaxation ororientation. Preferred materials are chemically reacted into a singlepolymeric specie such that a Differential Scanning Calorimeter analysisreveals a single polymeric material. Such a material, when combined witha preferred additive material, can form a surface coating of theadditive on the microfiber that provides oleophobicity, hydrophobicityor other associated improved stability when contacted with hightemperature, high humidity and difficult operating conditions. The finefiber of the class of materials can have a diameter of about 0.01 to 5microns. Such microfibers can have a smooth surface comprising adiscrete layer of the additive material or an outer coating of theadditive material that is partly solubilized or alloyed in the polymersurface, or both. Preferred materials for use in the blended polymericsystems include nylon 6; nylon 66; nylon 6-10; nylon (6-66-610)copolymers and other linear generally aliphatic nylon compositions. Apreferred nylon copolymer resin (SVP-651) was analyzed for molecularweight by the end group titration. (J. E. Walz and G. B. Taylor,determination of the molecular weight of nylon, Anal. Chem. Vol. 19,Number 7, pp 448-450 (1947). A number average molecular weight (M_(n))was between 21,500 and 24,800. The composition was estimated by thephase diagram of melt temperature of three component nylon, nylon 6about 45%, nylon 66 about 20% and nylon 610 about 25%. (Page 286, NylonPlastics Handbook, Melvin Kohan ed. Hanser Publisher, New York (1995)).Reported physical properties of SVP 651 resin are: Property ASTM MethodUnits Typical Value Specific Gravity D-792 —  1.08 Water AbsorptionD-570 %  2.5 (24 hr immersion) Hardness D-240 Shore D  65 Melting PointDSC ° C.(° F.) 154 (309) Tensile Strength D-638 MPa (kpsi)  50 (7.3) @Yield Elongation at Break D-638 % 350 Flexural Modulus D-790 MPa (kpsi)180 (26) Volume Resistivity D-257 ohm-cm  10¹²

[0028] We have found that additive materials can significantly improvethe properties of the polymer materials in the form of a fine fiber. Theresistance to the effects of heat, humidity, impact, mechanical stressand other negative environmental effect can be substantially improved bythe presence of additive materials. We have found that while processingthe microfiber materials of the invention, that the additive materialscan improve the oleophobic character, the hydrophobic character and canappear to aid in improving the chemical stability of the materials. Webelieve that the fine fibers of the invention in the form of amicrofiber are improved by the presence of these oleophobic andhydrophobic additives as these additives form a protective layercoating, ablative surface or penetrate the surface to some depth toimprove the nature of the polymeric material. We believe the importantcharacteristics of these materials are the presence of a stronglyhydrophobic group that can preferably also have oleophobic character.Strongly hydrophobic groups include fluorocarbon groups, hydrophobichydrocarbon surfactants or blocks and substantially hydrocarbonoligomeric compositions. These materials are manufactured incompositions that have a portion of the molecule that tends to becompatible with the polymer material affording typically a physical bondor association with the polymer while the strongly hydrophobic oroleophobic group, as a result of the association of the additive withthe polymer, forms a protective surface layer that resides on thesurface or becomes alloyed with or mixed with the polymer surfacelayers. For 0.2-micron fiber with 10% additive level, the surfacethickness is calculated to be around 50 Å, if the additive has migratedtoward the surface. Migration is believed to occur due to theincompatible nature of the oleophobic or hydrophobic groups in the bulkmaterial. A 50 Å thickness appears to be reasonable thickness forprotective coating. For 0.05-micron diameter fiber, 50 Å thicknesscorresponds to 20% mass. For 2 microns thickness fiber, 50 Å thicknesscorresponds to 2% mass. Preferably the additive materials are used at anamount of about 2 to 25 wt. %. Oligomeric additives that can be used incombination with the polymer materials of the invention includeoligomers having a molecular weight of about 500 to about 5000,preferably about 500 to about-3000 including fluoro-chemicals, nonionicsurfactants and low molecular weight resins or oligomers. A usefulmaterial for use as an additive material in the compositions of theinvention is tertiary butylphenol oligomers. Such materials tend to berelatively low molecular weight aromatic phenolic resins. Such resinsare phenolic polymers prepared by enzymatic oxidative coupling. Theabsence of methylene bridges result in unique chemical and physicalstability. These phenolic resins can be crosslinked with various aminesand epoxies and are compatible with a variety of polymer materials.Examples of these phenolic materials include Enzo-BPA , Enzo-BPA/phenol,Enzo-TBP, Enzo-COP and other related phenolics were obtained fromEnzymol International Inc., Columbus, Ohio.

[0029] An extremely wide variety of flexible fabric materials exist fordifferent cleaning and polishing applications. The durable nanofibersand microfibers described in this invention can be added to any of thefabrics. These fabrics can be woven or non-woven. The fabrics can besingle layer or multiplayer. Each layer can comprise a single componentwoven or non-woven fiber or a blended, woven or non-woven fiber. Thefabric layers can be combined with an interior non-fiber layer such as asponge, a scrubbing mesh layer, a film barrier layer or a reservoirlayer. The fabrics can be combined with a handle, support or a block toaid in cleaning or polishing. The wipes described in this invention canalso be used to substitute for existing fabric wiping materials givingthe significant advantage of improved performance. Cleaning andpolishing is improved due to their small diameter, while exhibitinggreater durability.

[0030] The wipe construction according to the present invention includesa first layer of a permeable fabric substrate having a first surface. Afirst layer of fine fiber is secured to the first surface of the firstlayer of fabric. Preferably the first layer of fabric comprises fibershaving an average diameter of at least 10 microns, typically andpreferably about 12 (or 14) to 30 microns. Also preferably the firstlayer of permeable fabric comprises a layer having a basis weight of nogreater than about 100 grams/meter ², preferably about 40 to 80 g/m²,and most preferably at least 20 g/m². Preferably the first layer ofpermeable fabric is at least —0.008 inch (200 microns) thick, andtypically and preferably is about 0.01 to 0.05 inch (10³ microns) thick.

[0031] The microfiber or nanofiber of the unit can be formed by thecommon electrostatic spinning process. Barris, U.S. Pat. No. 4,650,506,details the apparatus and method of the electro spinning process and isexpressly incorporated herein by reference. Apparatus used in suchprocess includes a reservoir in which the fine fiber forming polymersolution is contained, a pump and a rotary type emitting device oremitter to which the polymeric solution is pumped and applied. Theemitter generally consists of a rotating portion. The rotating portionthen obtains polymer solution from the reservoir, and as it rotates inthe electrostatic field, the electrostatic field, as discussed below,accelerates a droplet of the solution toward the collecting fabricsurface. Facing the emitter, but spaced apart therefrom, is asubstantially planar grid upon which the collecting surface (i.e. fabricor multilayer of multifiber fabric is positioned. Air can be drawnthrough the grid. The collecting surface is positioned adjacent oppositeends of grid. A high voltage electrostatic potential is maintainedbetween emitter and grid by means of a suitable electrostatic voltagesource.

[0032] In use, the polymer solution is pumped to the rotating portionfrom reservoir. The electrostatic potential between grid and the emitterimparts a charge to the material that cause liquid to be emittedtherefrom as thin fibers which are drawn toward grid where they arriveand are collected on substrate fabrics. In the case of the polymer insolution, solvent is evaporated off the fibers during their flight tothe grid; therefore, the fibers arrive at the fabric. The fine fibersbond to the fabric fibers first encountered at the grid. Electrostaticfield strength is selected to ensure that the polymer material as it isaccelerated from the emitter to the fabric; the acceleration issufficient to render the material into a very thin microfiber ornanofiber structure. Increasing or slowing the advance rate of thecollecting fabric can deposit more or less emitted fibers on the formingfabric, thereby allowing control of the thickness of each layerdeposited thereon.

[0033] The wipe of the invention can be pre-moistened (i.e.) combinedwith a liquid material and packaged in a container that maintains thewipe inn its pre-moistened condition. The container can comprise asingle use envelope or a multiuse pop-up dispenser or relatedcontainers. The liquid materials can include cleaners, disinfectingsolutions, decontaminating solutions, coating solutions, wax coatingsolutions, cosmetic solutions, human deodorant solutions, facialmoisturizers, facial cleaners, make-up removing solutions and othermaterials. Virtually any liquid cleaner composition or composition thatcan lay down a smooth coating can be combined with the wipes of theinvention.

[0034] The liquid material used for the wipe of the invention can be anaqueous based or solvent based material. Aqueous based materials aretypically manufactured by combining the active ingredient or formulationin an aqueous base. The aqueous base of the material can include solventmaterials that are soluble or dispersible in the aqueous media. Suchliquid materials used in the wipes of the invention can also be based onsolvent chemistry. Such solvents include alcohol, light petroleumdistillate, ketones, ethers and other typically volatile solventmaterials. Such liquids can also contain some small proportion of anaqueous material that can be either dissolved or suspended in thesolvent solution.

[0035] The liquid compositions of the invention can include surfactantmaterials, chelator materials, disinfectants, sanitizers, bleaches,lubricants, and other active materials that can act to either removesoil from surfaces or to provide a coating on the clean surfaces aftersoil removal. One important embodiment of the wipe of the inventionincludes a wipe that can form a useful coating on surfaces. Suchcoatings can comprise a wax, a polymeric material, a silicone wax orother coating material. One important advantage of the wipes of theinvention is the nanofiber material on the wipe can obtain an improvedsurface characteristic due to the small fiber size of the wipe finefiber layer. As the coating material is laid down by the wipe duringcleaning or cleaning and coating, the fine fiber size tends to form acoating layer with substantially reduced defect size in the coatinglayer resulting in an improved surface gloss or smoothness. Glasscleaner materials can include isopropanol and ammonium hydroxide andether solvents such as 2-butoxyethanol and ethylene glycol n-alkylether. A polish and cleaner can include paraffinic hydrocarbon solvent,silicone, naphtha solvent (petroleum distillate). Skin cleaner caninclude water, propylene glycol, PEG-75 Lanolin, Disodium anionicsurfactant, Polysorbate materials, Methylparaben,2-Bromo-2-Nitropropane-1, 3-Diol, Fragrance, etc. Facial cleaner wipescan include water, alcohol (10%), butylene glycol, laureth-(EO)_(x)nonionic, phenoxyethanol, salicylic acid, panthenol, propylene glycol,PEG-7, glyceryl cocoate, fragrance, PEG-substituted hydrogenated castoroil, disodium EDTA, benzoic acid, fragrance, menthol, t-butyl alcohol,etc. Hard surface cleaner wipes can contain quaternary ammoniumcompounds. Make-up remover wipes can include water, alkylene glycol,glycerin, herbal extract, vitamin-E acetate, aloe vera, panthenol,ginseng (panax ginseng) extract, anionic surfactant, benzyl alcohol,PEG-40 hydrogenated castor oil, alkylene glycol, polysorbate 20,fragrance, citric acid and DMDM hydantoin. Disinfectant wipes caninclude sodium hypochlorite, ethyl alcohol, Quats, etc.

EXPERIMENTAL

[0036] Examples 1, 2 and 3 show the preparation of a nanofiber layer ona wipe substrate. The wipe is tested for cleaning properties onautomotive surfaces to test the cleaning properties of the material withorganic and inorganic particulate soil.

[0037] The wipe substrate material used for the following examples wasmade from a blend of cellulose and polypropylene fibers, blended in sucha way as to make one side of the material predominantly cellulose, whilethe other side of the material is predominantly polypropylene. Thecomposite material has a basis weight of approximately 58 grams persquare meter and a thickness of approximately 0.016 inch.

Example 1

[0038] Polyamide fibers were electrospun onto the polypropylene-richside of a blended fiber wipes material (blend of polypropylene andcellulose). The fiber size was 0.25 micron having a basis weight of thenanofiber application was approximately 0.21 g-m⁻². The resultingmaterial was then used to wipe the dash panel of a 1995 Ford Contour(nanofiber side in contact with the windshield), by swiping the materialacross the dash panel, back and forth, 3 times in an approximate 14″path. The SEM's and analysis associated with this test are shown inFIGS. 1-4.

Example 2

[0039] Polyamide fibers were electrospun onto the polypropylene-richside of a blended fiber wipes material (blend of polypropylene andcellulose). The basis weight of the nanofiber application wasapproximately 0.21 g-m⁻², with a fiber size of approximately 0.25microns. The resulting material was then used to wipe the interiorwindshield of a 1995 Ford Contour (nanofiber side in contact with thewindshield), by wiping in a circular motion (approximate 8″ diametercircle) 3 times, followed by wiping back and forth over the same area ofthe windshield 3 times, in a 10″ path. The SEM's and analysis associatedwith this test are FIGS. 5-11.

Example 3

[0040] Polyamide fibers were electrospun onto the cellulose-rich side ofa blended fiber wipes material (blend of polypropylene and cellulose).The basis weight of the nanofiber application was approximately 0.21g-m⁻², with a fiber size of approximately 0.25 microns. The resultingmaterial was then used to wipe the dash panel of a 1995 Ford Contour(nanofiber side in contact with the windshield), by swiping the materialacross the dash panel, back and forth, 3 times in an approximate 14″path. The scanning electro micrographs and analysis associated with thistest are shown in FIGS. 12-17.

Automotive Dash Testing FIGS. 1-4

[0041] Nanofibers were applied to the polypropylene side of the twolayer cellulosic/polypropylene material. The wipe was tested by its usein an automobile and was wiped on a vehicle dash.

[0042] In FIG. 1, at ×200 magnification, we see dirt, particulate 10sized as 50-70 μm, with many much smaller particulate in the nanofiberweb 11. Fabric substrate 12 is shown in the background. Much of thenanofiber web 11 is discontinuous and dirt covered. In FIG. 2, at ×1500magnification, we see soil particles 20 and nanofiber 21 wound and boundtogether with substrate fabric fiber 23 in background. Some portion ofthe particles is held in nanofiber/particulate bundle 24. Otherparticulate 25 is adhered to the surface of the nanofibers, presumablythrough Van der Waal's forces. In FIG. 3, at ×5000 magnification, we cansee dirt particulate 30 bundled in the discontinuous nanofiber web 31.In FIG. 1, at ×200 magnification again, in places where the nanofiberweb is gone, dirt is migrated into the depth of the substrate past thenanofiber layer where particulate wedges between fibers. Small particlesare clearly preferentially retained by nanofiber versus largerparticulate in larger fibers. In FIG. 4, at ×10,000 magnification, dirtparticulate 40 is shown wound up in nanofiber 41. We see particles 42about 0.2 μm in size.

Automotive Window Testing FIGS. 5-7

[0043] Sample is nanofibers applied to the polypropylene side of the twolayer non-woven, wiped on vehicle interior window.

[0044] In FIG. 5, at ×200 magnification, we see much less dust and dirt52, than FIGS. 1-4, most of the nanofiber web 50 is still substantiallyintact due reduced abrasion from particulate from a cleaner surface.Fabric substrate fiber 51 is in background. In FIG. 6, at ×2500magnification, we see an area of rolled-up nanofiber 60 adjacent tonanofiber web 62, with a coating of agglomerated substantially organicsoil or contaminant 61 on the nanofiber. The window soil is not largelyinorganic particulate, but is greasy, organic matter that coats thefiber as compared to the dry particulate on the dash that is enmeshed byor entangled in the nanofiber. The organic soil is easily picked up bythe nanofiber web, which provides a substantial of surface area contactand a compatible surface. In FIG. 7, at ×10000 magnification, we see aclose-up picture of the organic soil 61 coating the fiber with adjacentnanofiber 70 and web 71.

Automotive Window Testing FIGS. 8-11

[0045] In FIG. 8 at ×200 magnification, we see most of the web structure80 intact, with little particulate 81 or contaminant.

[0046] In FIG. 9 at ×1000 magnification, we see some contaminantparticles 90 on the web 91, some on the fiber of substrate surface 92.We can also see areas where nanofiber web is discontinuous. The largesubstrate fiber 92 without a nanofiber covering suggests that it hasmoved from its original location, driving, wiping. There is alsoevidence of organic contaminant 93 collected on the nanofiber webportion bonded to the substrate fibers. In FIG. 10 at ×4000magnification, we see organic contaminant 100 on nanofibers 101, as wellas some particulate 102 that has been captured/wedged behind thenanofiber structure. In FIG. 11 at ×17000 magnification, we see thecaptured/wedged particle 102 behind nanofiber 110. We can discerncontaminants as small as 0.05-0.1 μm. There is also a coiled-up sectionof nanofibers agglomerated with particles and organic soil 111 bundledin a fiber web.

Automotive Dash Testing FIGS. 12-14

[0047] Sample is nanofibers on pulp side wiped on dash.

[0048]FIG. 12 at ×200 magnification, we see that more of the nanofiberweb is intact than samples in FIGS. 1-4. There is a lot of particulate120, some areas of exposed substrate fiber 121 and discontinuousnanofiber web 122. FIG. 13 at ×1000 magnification, we see that manyparticles 130 are collected on the nanofiber web surface 131, but thatsome particles 132 have been captured between the nanofiber layer andthe substrate fibers or in the fabric. Particulate can move into thedepth through nanofiber web hole and migrate behind. FIG. 14 at ×4000magnification, we see a close-up of the particle 132 behind the web 140,with other particulate 141 on top. Particulate 142, as small as 0.5 μm,can be seen held or entangled in the fiber. FIG. 13 at ×1000magnification again, we see a particle underneath the nanofiber web, asfar as 50 μm away from a hole large enough to allow its passage.

Automotive Dash Testing FIGS. 15-17

[0049] Sample is nanofibers applied to pulp side, wiped across dash.

[0050] In FIG. 15 at ×200 magnification, we see most of nanofiber web150 intact with some holes 151 and discontinuous areas. In FIG. 16 at×1500 magnification, we see a few particles 160 wrapped up in nanofibers161. We see a large (20-30 μm) particle 162 sitting on top of thenanofiber web. We see a large substrate fiber 163 that has captured fewa particles 164 on its surface. In FIG. 17 at ×6000 magnification, wesee a close-up of the captured particles 160 and the nanofiber web 161.In FIG. 16 at ×1500 magnification again, we see a particle lodgedunderneath the nanofiber web. This particle is perhaps 30 μm away fromthe nearest web discontinuity that is sufficiently sized to allow itspassage.

[0051] In previously filed applications, the formation of fine fiberlayers on filtration media has been disclosed. Such filter structuresare different than a wipe structure. In order to establish a cleardistinction between a wipe material and a filtration structure, a numberof consumer wipe materials were purchased and tested for stiffnesscharacteristics. Filtration media must have characteristic stiffness tooperate in the filtration environment in which a stream of liquid or gaspasses through the filter and particulate is removed. The media must bestiff enough to survive the mechanical stress placed on the filter mediaby the moving fluid. Both dry and wet wipes were tested. Wet wipes werewashed and dried before testing for stiffness.

[0052] Wipes substrates tested—wet (all were soaked in filtereddeionized water at room temperature for 10 minutes, with three waterchange-out, then dried in an oven at 85° C. for 10 minutes). Rain-XGlass cleaner with Anti-Fog Wipes—Rain-X; Rain-X Wipes; Wet OnesAntibacterial Wipes—Playtex Products Inc. Pledge Wipes—S.C. Johnson &Son, Inc. Clorox Disinfecting Wipes—The Clorox Company Windex Glass andSurface Wipes—S.C. Johnson & Son, Inc. Clean & Clear Deep ActionCleansing Wipes _Johnson & Johnson Pond's Cleansing and Make-Up RemoverTowelettes—Chesebrough-Pond's USA Co. Wipes materials tested—dry Swifferdisposable cloths—Proctor & Gamble Pledge Grab-It dry cloths—S.C.Johnson & Son, Inc. Each sample was tested for stiffness according toTAPPI T-543 om-00: “Bending Resistance of Paper (Gurley-Type Tester)”.In performing the test, a bending resistance/stiffness test instrumentis used that consists of a balanced pendulum or pointer which iscenter-pivoted and can be weighted at three points below its center. Thepointer moves freely in both left and right directions on cylindricaljewel bearings which make the mechanism highly sensitive even tolight-weighted materials.

[0053] A sample of a specific size is attached to a clamp, which in turnis located on a motorized arm, which also moves left and right. Thebottom 0.25 inch of the sample overlaps the top of the pointer (atriangular shaped “vane”). During the test the sample is moved againstthe top edge of the vane, moving the pendulum until the sample bends andreleases it.

[0054] On digital models, the point of release is automatically measuredby an optical encoder and displayed on a digital readout. this readoutcontinuously displays readings from tests performed in both the left andright directions. In addition, the on-board microprocessor automaticallycomputes and displays the average of left and right stiffness data aftereach measurement is performed. For flat sheet materials, the operatorcan then press a button to automatically convert the point-of-releasereading on the display to force (milligrams).

[0055] However, none of the material samples had sufficient stiffness tobe measured using this method. The minimum stiffness value that can beaccurately measured on this Gurley stiffness tester is approximately 300mg. As such, the stiffness of each of these materials is known to beless than 300 mg. Typical stiffness values for other filter media typesare about 350-12,000 mg.

[0056] The foregoing constitutes a complete description of theembodiments of the invention recognized to date. However, since theinvention can reside in a variety of embodiments without departing fromthe spirit and scope of the invention, the invention resides in theclaims hereinafter appended.

We claim:
 1. A wipe conformable to a surface, the wipe comprising atleast a flexible substrate and a nanofiber layer, the flexible substratecomprising a layer having a thickness of about 0.01 to 0.2 cm, thenanofiber layer comprising fiber having a diameter of about 0.001 toabout 1 micron, a basis weight of about 0.0012 to about 3.5 grams-m⁻²,the layer having a pore size less than about 20 microns.
 2. The wipe ofclaim 1 wherein the wipe comprises a woven fabric having a thickness ofabout 0.02 to 0.1 cm and a nanofiber layer having a fiber size of about0.05 to 0.5 micron and a basis weight of about 0.1 to 0.5 gm-m⁻².
 3. Thewipe of claim 1 wherein the wipe comprises a cellulosic non-woven havinga thickness of about 0.02 to 0.1 cm and a nanofiber layer having a fibersize of about 0.05 to 0.5 micron and a basis weight of about 0.1 to 0.5gm-m⁻².
 4. The wipe of claim 1 wherein the wipe comprises a blendedpolymer cellulosic non-woven having a thickness of about 0.02 to 0.1 cmand a nanofiber layer having a fiber size of about 0.05 to 0.5 micronand a basis weight of about 0.1 to 0.5 gm-m⁻².
 5. The wipe of claim 1wherein the substrate comprises a non-woven fabric made from bothcellulosic and polymeric fiber materials.
 6. The wipe of claim 1 whereinthe wipe has a stiffness measured according to TAPPI T 543 om-00:“Bending Resistance of Paper (Gurley-Type Tester)” less than 300milligrams.
 7. The wipe of claim 1 wherein the wipe is combined with aliquid cleaner material wherein the nanofiber layer in contact with soilcan incorporate the soil particulate into the nanofiber layer forimproved cleaning.
 8. The wipe of claim 1 wherein the wipe is combinedwith a liquid lubricant.
 9. The wipe of claim 1 wherein the wipe iscombined with a liquid coating composition.
 10. The wipe of claim 7wherein the liquid cleaner material comprises an aqueous cleaner.
 11. Awipe conformable to a surface, the wipe comprising at least a flexiblesubstrate having a first and a second side and a non-woven nanofiberlayer on both the first and the second side, the flexible substratecomprising a layer having a thickness of about 0.01 to 0.2 cm, thenanofiber comprises a layer comprising fiber having a diameter of about0.001 to about 1 micron, a basis weight of about 0.0012 to about 3.5grams-m⁻², the layer having a pore size less than about 20 microns. 12.The wipe of claim 11 wherein the wipe comprises a woven fabric having athickness of about 0.02 to 0.1 cm and a nanofiber layer having a fibersize of about 0.05 to 0.5 micron and a basis weight of about 0.1 to 0.5gm-m⁻².
 13. The wipe of claim 11 wherein the wipe comprises a cellulosicnon-woven having a thickness of about 0.02 to 0.1 cm and a nanofiberlayer having a fiber size of about 0.05 to 0.5 micron and a basis weightof about 0.1 to 0.5 gm-m⁻².
 14. The wipe of claim 11 wherein the wipecomprises a blended polymer cellulosic non-woven having a thickness ofabout 0.02 to 0.1 cm and a nanofiber layer having a fiber size of about0.05 to 0.5 micron and a basis weight of about 0.1 to 0.5 gm-m⁻². 15.The wipe of claim 11 wherein the substrate comprises a non-woven fabricmade from both cellulosic and polymeric fiber materials.
 16. The wipe ofclaim 11 wherein the wipe has stiffness measured according to TAPPI T543 om-00: “Bending Resistance of Paper (Gurley-Type Tester)” less than300 milligrams.
 17. The wipe of claim 11 wherein the wipe is combinedwith a liquid cleaner material wherein the nanofiber layer in contactwith soil can incorporate the soil particulate into the nanofiber layerfor improved cleaning.
 18. The wipe of claim 11 wherein the wipe iscombined with a liquid lubricant.
 19. The wipe of claim 11 wherein thewipe is combined with a liquid coating composition.
 20. The wipe ofclaim 17 wherein the liquid cleaner material comprises an aqueouscleaner.
 21. A film forming polishing wipe conformable to a surface, thewipe comprising a film forming composition, at least a flexiblesubstrate and a nanofiber layer, the flexible substrate comprising alayer having a thickness of about 0.01 to 0.2 cm, the nanofiber layercomprising fiber having a diameter of about 0.001 to about 1 micron, abasis weight of about 0.0012 to about 3.5 grams-m⁻², the layer having apore size less than about 20 microns.
 22. The wipe of claim 21 whereinthe wipe comprises a woven fabric having a thickness of about 0.02 to0.1 cm and a nanofiber layer having a fiber size of about 0.05 to 0.5micron and a basis weight of about 0.1 to 0.5 gm-m⁻².
 23. The wipe ofclaim 21 wherein the wipe comprises a cellulosic non-woven having athickness of about 0.02 to 0.1 cm and a nanofiber layer having a fibersize of about 0.05 to 0.5 micron and a basis weight of about 0.1 to 0.5gm-m⁻².
 24. The wipe of claim 21 wherein the wipe comprises a blendedpolymer cellulosic non-woven having a thickness of about 0.02 to 0.1 cmand a nanofiber layer having a fiber size of about 0.05 to 0.5 micronand a basis weight of about 0.1 to 0.5 gm-m⁻².
 25. The wipe of claim 21wherein the substrate comprises a non-woven fabric made from bothcellulosic and polymeric fiber materials.
 26. The wipe of claim 21wherein the wipe has stiffness measured according to TAPPI T 543 om-00:“Bending Resistance of Paper (Gurley-Type Tester)” less than 300milligrams.
 27. The wipe of claim 21 wherein the wipe is combined with aliquid coating composition.
 28. The wipe of claim 27 wherein the wipe iscombined with an aqueous coating composition.